Concrete bridge superstructure



s??? 6, L. TURNER I gg gg CONCRETE BRIDGE SUPERSTRUCTURE Filed Nov. 18, 1944 uzvzezf Patented Aug. 6, 1946 UNl-TED STATES OFFICE CONCRETE BRIDGE SUPERSTRUCTURE William L. Turner, San Antonio, 'llex., assignor of one-half to Bart Moore, Jr., San Antonio, Tex.

1 Claim. 1

The object of the present invention is to provide a method of constructing bridge superstructures in such manner as to save a great deal of lumber and a great deal of labor. Under the proposed method the use of form lumber in the formation of concrete bridge superstructures is largely eliminated. Briefly stated, the invention resides in the provision of a plurality of pre-cast concrete girders which, when placed side by side, complementally form the bridge superstructure. After these girders are in place the floor of the bridge is formed by pouring a reinforced concrete slab which extends across and ties together and is supported by all of the girders. This poured slab is given the desired crown or slope and thus all roughness caused by abutting girders is eliminated. Further, under this method the weight of heavily loaded trucks or the like i transmitted to and supported by several of the supporting girders. The invention also contemplates the formation of girders which, while of arch formation throughout the major portion of their length, are provided with closure web walls at their ends. These web Walls not only strengthen the girders at their ends, i. e., at the point at which the girders rest upon the pier cap, but they provide portions through which anchoring rods may extend from the concrete slab to the pier cap. Further objects and advantages of the invention will be set forth after a consideration of the forms illustrated in the accompanying drawing.

In the drawing Fig. 1 is a transverse section through a bridge superstructure constructed in accordance with the invention, and

Fig. 2 is a vertical sectional view through the pier cap showing the ends of two girders supported thereon.

The superstructure is supported upon any desired form of abutment or pier comprising the transverse cap 5 and piles 6. The elements 5 and 6 may be of either wood or concrete and it is to be understood that the particular form of pier or abutment forms no part of the invention.

In carrying out the invention I pre-cast a plurality of girders l and 3. The girders l are the inner girders and the girders 8 are the two outside girders. The girders l are substantially T- shaped in cross-section to provide the vertical shank portions and the horizontal head portions, said head portions abutting each other at their edges. These girders may be internally reinforced in any desired manner, the particular manner of reinforcement being a matter of choice. The particular shape of the arches is also a matter of choice since these may be varied within wide ranges. I have indicated reinforcing rods 9 and H] in the inner girders 1 but their specific arrangement is a matter of no particular importance, since the insertion of reinforcing rods in any desired direction is manifestly a matter of engineering choice. The several girders are preferably so shaped that when laid together side by side they form the arches II. This gives a structure of light weight but great strength. The outside girders are preferably provided with the curbings l2 and they are shouldered at l3 and recessed at I4 to receive the ends of the slab l5 which is preferably of concrete but may be made of any poured road forming material. The slab I5 is suitably crowned and since it covers all of the joints between the girders, it follows that any unevenness at the joints between the girders does not follow through to the wearing surface of the slab. Reinforcing elements or dowels l6 and I! extend horizontally in the slab and outer girders and tie the whole structure together. These reinforcing members may be two separate rods or they may be connected by a bend it. In constructing a bridge under the method hereindescribed, the girders may be precast, as at a factory, brought to the bridge site and lifted by derrick into the position illustrated by the drawing. The girders may be made of a length to suit the particular bridge under construction. When laid together side by side they serve not only as girders but as a form into which the slab I5 is poured. Thus the expensive forms so frequently employed in the construction of concrete bridges are, by thi method rendered unnecessary. Further, it will be observed that the vertical reinforcing rods 9 tie the slab to each individual girder. While the arch formation of the girders may extend the full length thereof, if desired, I prefer to closs the ends of the arches by web walls l8 which overlie the cap 5 of the pier. Vertica1 anchor rods i9 extend through these web walls and tie the slab to the cap plate. These web walls serve to house these anchor rods and protect them from the weather.

I am aware of the fact that it has heretofore been proposed to construct bridges by the use of a plurality of girders laid side by side. However, as far as I am aware I am the first to provide such an arrangement as that wherein the wear receiving slab constituting the roadway proper is common to all of the girders and serves not only its function of a Wear receiving slab but as a uniting means between all of the girders. Further, as far as I am aware I am the first to provide a structure such as described wherein the road forming slab is tied to the pier cap, as described, the binding means, in turn, serving to reinforce and secure the road forming slab in place.

Therefore, it is to be understood that the invention is not limited to the precise construction set forth but that it includes within its purview whatever changes fairly come within either the terms or the spirit of the appended claim.

Having described my invention, what I claim is:

A concrete bridge superstructure composed of a plurality of inner girders and a pair of outer girders laid together side by side, said inner girders being of substantially T-shape in cross-section,

so that the edges of their head, portions may con 7 tact to cause their upper surfaces to present a continuous floor while leaving open arches between said inner girders, said outer girders comprising portions which lie at the level of the floor presented by the tops of the inner girders and additional portions which lie at a higher level and a road forming slab laid upon the floor presented by the tops of the inner girders and the portions of lower level of the outer girders, said slab tying together all the T-shaped girders and the pair of outer girders, the top of said slab adjacent its outer edges lying at the level of the portions of higher level of the outer girders, and curb portions upon the outer girders which extend above the portion of higher level of said outer girders.

' I WILLIAM L. TURNER. 

